Tham khảo tài liệu 'lego mindstorms - the unofficial guide to robots - jonathan b. knudsen part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 30 This means that you can t simply connect the two drive wheels with a shaft and hook it up to a motor. You need something trickier called a differential not the same as differential drive . A simple variation on the car design is the tricycle design. In this design a single wheel instead of a pair is used for steering. Exotic Drives There are three other interesting drives that should be mentioned. The first of these is synchro drive. In this scheme the robot has three or more identical wheels. Each of the wheels pivots on its vertical center. All of the wheels point in the same direction. as shown in Figure 2-11. Figure 2-11. Synchro drive To turn the robot swivels the wheels to point in a new direction. This has the interesting side effect that the robot can change direction even though its body stays oriented the same. This property could be useful for robots that need to communicate with the computer over the IR link. The key to building synchro drive robots is a piece called a large turntable. You can order these pieces from Pitsco LEGO DACTA see Appendix A Finding Parts and Programming Environments for details. The tri-star wheel is another interesting idea. Figure 2-12 shows a side view of a tri-star robot and a close-up of the wheel assembly. Figure 2-12. Side view of the tri-star design 31 Each wheel assembly is actually composed of three wheels arranged in a triangular fashion. The robot drives these wheels to move. When a large obstacle like a step is encountered the entire wheel assembly rolls on its center axis. In essence the entire wheel assembly acts like a large triangular wheel. This large wheel size enables the tri-star design to drive over large obstacles. Killough splatform is an interesting variation on the wheels-within-a-wheel concept. It s really too exotic to describe here the Online Resources lists two web pages that contain photographs and diagrams of this platform. Bumpers and Feelers Hank uses the touch sensors to figure out when he
